Optical glass for precision molding

Abstract

The present invention provides an optical glass for precision molding, having excellent properties, i.e. yield temperature (At) of at most 550° C., refractive index (nd) of at least 1.83 and Abbe number (νd) of at most 26.0 and further providing a low softening property as well as an improved mass production property with less coloration, which is represented, in term of atoms for making up the glass, by the following chemical composition (wt %)

What is claimed is:  
     
       1. A high refractive index, high dispersion optical glass or precision molding, having a yield temperature (At) of at most 550° C., refractive index (nd) of at least 1.83 and Abbe number (νd) of at most 26.0, which is represented, in term of atoms for making up the glass, by the following chemical composition (wt %): 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   P 2 O 5   
                   14.0 to 31.0% 
                 
                     
                   B 2 O 3   
                     0 to 5.0% 
                 
                     
                   GeO 2   
                     0 to 14.0% 
                 
                     
                   Sum of P 2 O 5  + B 2 O 3  + GeO 2   
                   14.0 to 35.0% 
                 
                     
                   Li 2 O 
                     0 to 6.0% 
                 
                     
                   Na 2 O 
                    2.5 to 14.0% 
                 
                     
                   Sum of Li 2 O + Na 2 O 
                    2.5 to 15.0% 
                 
                     
                   Nb 2 O 5   
                   25.0 to 50.0% 
                 
                     
                   WO 3   
                     0 to 30.0% 
                 
                     
                   Bi 2 O 3   
                    5.0 to 36.0% 
                 
                     
                   BaO 
                     0 to 22.0%. 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
       
     
     
       2. A high refractive index, high dispersion optical glass for precision molding, having a yield temperature (At) of at most 550° C., refractive index (nd) of at least 1.83 and Abbe number (νd) of at most 26.0, which is represented, in term of atoms for making up the glass, by the following chemical composition (wt %): 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   P 2 O 5   
                   15.0 to 30.0% 
                 
                     
                   B 2 O 3   
                     0 to 4.0% 
                 
                     
                   GeO 2   
                     0 to 12.0% 
                 
                     
                   Sum of P 2 O 5  + B 2 O 3  + GeO 2   
                   17.0 to 30.0% 
                 
                     
                   Li 2 O 
                     0 to 5.0% 
                 
                     
                   Na 2 O 
                    5.0 to 13.0% 
                 
                     
                   Sum of Li 2 O + Na 2 O 
                    5.0 to 14.0% 
                 
                     
                   Nb 2 O 5   
                   25.0 to 45.0% 
                 
                     
                   WO 3   
                     0 to 20.0% 
                 
                     
                   Bi 2 O 3   
                    6.0 to 30.0% 
                 
                     
                   BaO 
                     0 to 15.0%.